Method of manufacturing electric lamps bases for carrying out said method and lamps thus obtained

ABSTRACT

A METHOD OF MANUFACTURING AN ELECTRIC LAMP OF WHICH THE BULB HAS FORMED IN ITS NECK PORTION A PAIR OF SEPARATE GROOVES EXTENDING IN A COMMON TRANSVERSE PLANE. ACCORDING TO SAID METHOD EACH LAMP BASE IS MADE OF A SUITABLE FLEXIBLE MATERIAL BY FORMING IN THE BASE SKIRT ON THE ONE HAND A PAIR OF INTERNAL ANCHORING BEADS ADAPTED TO FIT INTO THE GROOVES OF THE BULB NECK AND ON THE OTHER HAND ONE OR TWO LONGITUDINAL SLITS. THEN, THIS BASE IS FITTED TO THE BULB NECK BY MOMENTARILY EXPANDING THE PORTIONS OF THE BASE SHIRT WHICH ARE FORMED THEREIN BY SAID SLIT OR SLITS, SO THAT THE INTERNAL ANCHORING BEADS OF SAID SKIRT CAN FIT INTO THE GROOVES OF THE BULB NECK. FINALLY, THE EDGES OF THE LONGITUDINAL SLIT OR SLITS FORMED IN THE BASE SKIRT ARE SEALED TOGETHER. THIS DISCLOSURE IS ALSO CONCERNED WITH LAMP BASES DESIGNED FOR CARRYING OUT THE MANUFACTURING METHOD SET FORTH HEREINABOVE, AND WITH ELECTRIC LAMPS MANUFACTURING BY CARRYING OUT THIS METHOD.

NORTH, 1971 J E ER METHOD OF MANUFACTURING ELECTRIC LAMPS. BASES FOR CARRYING OUT SAID METHOD AND LAMPS THUS OBTAINED Filed May 22, 1969 2 Sheets-Sheet 1 JI B lawn/74A BM 6 /3 M4M RNEY;

Nov. 16, 1971 J. BESACIER METHOD OF MANUFACTURING ELECTRIC LAMPS, BASES FOR CARRYING OUT SAID METHOD AND LAMPS THUS OBTAINED 2 Sheets-Sheet 8 Filed May 22, 1.969

Jun 13 sa e ZBuQVM Btu/w. I Arman:

United States Patent Ofice 3,619,876 Patented Nov. 16, 1971 US. Cl. 2925.13 2 Claims ABSTRACT OF THE DISCLOSURE A method of manufacturing an electric lamp of which the bulb has formed in its neck portion a pair of separate grooves extending in a common transverse plane. According to said method each lamp base is made of a suitable flexible material by forming in the base skirt on the one hand a pair of internal anchoring beads adapted to fit into the grooves of the bulb neck and on the other hand one or two longitudinal slits. Then, this base is fitted to the bulb neck by momentarily expanding the portions of the base skirt which are formed therein by said slit or slits, so that the internal anchoring beads of said skirt can fit into the grooves of the bulb neck. Finally, the edges of the longitudinal slit or slits formed in the base skirt are sealed together.

This disclosure is also concerned with lamp bases designed for carrying out the manufacturing method set forth hereinabove, and with electric lamps manufacturing by carrying out this method.

The present invention relates to electric lamps where in the bulb comprises a base attached to its neck.

Up to now bases of this type are sealed to the lamp bulb by means of a special base paste. However, in order to reduce manufacturing cost, it has already been proposed to use moulded plastic bases secured to the bulb by mechanical means, in order to avoid the use of base sealing paste. Nevertheless, the fastening means thus contemplated are not quite convenient and not fully satis factory.

It is therefore the essential object of the present invention to provide a method of manufacturing electric lamps which is so arranged that their bases can be secured to the neck of the bulbs without difiiculty by using indus trial methods and at a reduced cost.

The present method is directed to the manufacture of electric lamps wherein the bulb has formed in its -neck portion a pair of separate grooves extending in a common transverse plane. This method is characterized in that each lamp base is made of a suitable flexible material by forming in the base skirt on the one hand a pair of internal anchoring beads adapted to fit into the grooves of the bulb neck and on the other hand one or two longitudinal slits. Then, this base is fitted to the bulb neck by momentarily expanding the portions of the base skirt which are formed therein by said slit or slits, so that the internal anchoring beads of said skirt can fit into the grooves of the bulb neck. Finally, the edges of the longitudinal slit or slits formed in the base skirt are sealed together.

This sealing operation may be performed by welding the edges under the action of heat, for example by induction electric heating, or by using an ultrasonic vibration method.

This invention is also concerned with lamp bases designed for carrying out the manufacturing method set forth hereinabove. Each lamp base is characterized in that its skirt comprises on the one hand internal anchoring beads adapted to engage corresponding grooves formed in the neck of the relevant bulb, and on the other hand one or a plurality of longitudinal slits forming skirt portions adapted to be momentarily expanded when fitting said base on the bulb neck.

Of course, this invention is also concerned with electric lamps provided with bases of the type broadly de scribed hereinabove, and manufactured by carrying out the method set forth in the foregoing.

Besides, a typical form of embodiment of an electric lamp manufactured according to this invention will now be described by way of illustration with reference to the attached drawing, in which:

FIG. 1 is an elevational view with parts broken away showing a base according to this invention, with a corresponding electric lamp bulb disposed underneath;

FIG. 2 illustrates in section the same base and in elevation the corresponding side portion of the bulb of the electric lamp;

FIG. 3 is a section taken along the line IIIIII of FIG. 1;

FIG. 4 is an elevational view with parts broken away illustrating the manufacturing phase during which the base of this invention is secured to the neck of an electric lamp bulb;

FIG. 5 is a corresponding sectional view, taken along the line V-V of FIG. 4; and

FIG. 6 is a fragmentary elevational view, with parts broken away, of an electric lamp bulb equipped with a base according to this invention.

In the example illustrated in the attached drawing the lamp base 1 is of the so-called bayonet type. In fact, it comprises a pair of diametrally opposite pins 2 adapted to engage corresponding notches formed in a lamp socket for holding the lamp therein. This base is manufactured by moulding a suitable plastic material and the pins 2 may be produced in any desired and suitable manner. However, this base could also be of the Edison or screw type.

The lamp base according to this invention is adapted to be fastened to the neck 3 of an electric lamp bulb 4. More particularly, it is adapted to equip a bulb having formed in its neck portion a pair of retaining grooves 5 spaced from each other but extending in a common transverse plane. In this respect it may be noted that bulbs of this kind correspond to a now currently manufactured bulb type adapted to receive a conventional base sealed in position thereon by using base sealing paste.

According to an essential feature characterizing this invention the base 1 comprises on its inner wall a pair of anchoring beads 6 adapted to engage the aforesaid grooves 5 of lamp bulb 4. However, the skirt of this base has formed therein a plurality of longitudinal slits 7 extending from its bulb-engaging into end to one fraction of the length of this skirt. In the example illustrated these slits are two in number and their position is such that each one extends substantially across the middle of one of the aforesaid anchoring beads 6.

The provision of these two slits will thus permit the snap engagement of the base on the neck portions 3 of the lamp bulb in spite of the presence of the pair of anchoring beads 6. In fact, due to these slits the two skirt portions formed therebetween can resiliently be moved away from each other or expanded, so that the base can be fitted to the neck 3 of the electric lamp bulb by snap action, provided that the base is inserted in a proper angular position i.e. the position permitting the engagement of said anchoring beads 6 in said grooves 5-.

Upon completion of this insertion the only step required consists in sealing together the pair of lips or edges of each slit 7 so that the base be definitely fastened to the neck portion of the lamp bulb. However, this sealing action can be performed in various manners.

Preferably, the registering edges or lips of each slit 7 are sealed together by thermal effect, for example according to the well known supersonic vibration welding meth od. In this case, the assembly is disposed between the fixed block 8 and the vibration head 9 of a machine of known type designed for welding plastic articles according to this method. Of course, the shapes of these fixed block and vibration heads 8, 19 are specially designed for performing this specific application. Thus, these two members will firstly reduce the gap formed between the lips or edge of each slit, and subsequently weld them together.

Under these conditions, when the lamp is removed from the welding machine or unit, the skirt of base 1 is an integral cylindrical member. Therefore, its anchoring beads 6 cannot be released from the relevant grooves S of the bulb neck, so that the base is definitely sealed thereto. Of course, before carrying out the final sealing step and therefore fastening the base 1 to the bulb, the ends 11 of the lamp filament already mounted in the bulb must be connected in the usual manner to the lead-in conductors and eventually to the outer contacts 12 of this base.

In this respect it may be noted that the welding of the lips or edges of each slit 7 of the base of this invention is likely to result in a crack extending from each slit to the outer wall of the base 1. To avoid this inconvenience it is advantageous to provide from the onset a groove formed on the outer surface of the skirt, each groove 10 registering with and corresponding in. length to the relevant slit 7 (see FIG. 3).

With the manufacturing method of this invention the lamp bases can easily be fitted on the lamp bulbs by resorting to industrial means affording high production rates. Now the use of the bases according to this invention also affords a considerable reduction in the cost of the thus manufactured electric lamps which are further characterized by the advantageous features inherent to the use of plastic bases.

Thus, the lips or edges of the longitudinal slits 7 may be welded or sealed according to a different method, for example by cementing them by means of a suitable glue or cement, or even by using a suitable solvent. However, this sealing or welding step may also be carried out by heat welding, according to the well known induction or highfrequency welding process. Besides, the same operation may also be carried out successfully by fitting on the skirt a binding ring (not shown) consisting of any suitable material. Possibly, this binding ring may consist of plastic material and be formed by direct moulding on the base after the latter has been properly positioned on the neck of lamp bulb 4.

0n the other hand, the number and relative arrangement of the longitudinal slits formed in the skirt portion of said base may be modified without departing from the domain of this invention. Alternately, a single longitudinal slit located between two anchoring beads 6 formed on the inner wall of the base may be provided, if desired.

Moreover, the edge of the base which is adjacent to the bulb neck may comprise a reinforcing element consisting for example of a pair of metal wire sections embedded in the anchoring head 6 for the purpose of further increasing the adherence of the lamp base to the lamp bulb neck.

As already set forth hereinabove, the lamp base according to this invention may be of the bayonet type, or of the screw or Edison type. Finally, this lamp may be designed to constitute one of the opposite end bases of a tubular electric lamp such as a fluorescent tube.

I claim:

1. A method of manufacturing an electric lamp of which the bulb has formed in its neck portion a pair of separate grooves extending in a common transverse plane, said method comprising in combination the step of making a separate base with a thermoplastic material, said base being adapted to surround said bulb neck, providing on the skirt of said base a pair of internal anchoring beads adapted to engage said grooves in said bulb neck and at least one longitudinal slit, fitting said base to the bulb neck by momentarily expanding the portions of the base skirt which result from the presence of the slit formed therein, engaging the inner anchoring beads of said skirt in said grooves of the bulb neck, and welding the edges of the aforesaid longitudinal slit of the base skirt together, said welding being carried out by supplying heat to said skirt to cause said slits to melt and weld together.

2. The method according to claim 1 wherein said heat is applied to said beads to firmly anchor said base to said bulb.

References Cited UNITED STATES PATENTS 259,017 6/1882 Houston 29-2513 X 2,056,157 10/ 1936 Buttolph 29-25.l3 X 2,262,629 11/1941 Wright 29-2513 X 430,437 6/1890 Rockwell 339l44 2,896,306 7/1959 Eberiel et al. 2925.11 3,093,768 6/ 1963 Ayres 339-144 X 3,156,841 11/1964 Ayres 339'-144 X 3,173,735 3/1965 Fenn 339l44 3,431,540 3/1969 Kopelman 339-l45 X 3,497,745 2/1970 Boeing 2-925.ll X

JOHN F. CAMPBELL, Primary Examiner R. B. LAZARUS, Assistant Examiner US. Cl. X.R. 

